/*      $NetBSD: re.c,v 1.22 2025/09/17 20:35:11 rillig Exp $   */

/* re.c: This file contains the regular expression interface routines for
   the ed line editor. */
/*-
 * Copyright (c) 1993 Andrew Moore, Talke Studio.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#ifndef lint
#if 0
static char *rcsid = "@(#)re.c,v 1.6 1994/02/01 00:34:43 alm Exp";
#else
__RCSID("$NetBSD: re.c,v 1.22 2025/09/17 20:35:11 rillig Exp $");
#endif
#endif /* not lint */

#include <stdarg.h>
#include "ed.h"


char errmsg[MAXPATHLEN + 40] = "";

void
seterrmsg(const char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        vsnprintf(errmsg, sizeof(errmsg), fmt, ap);
        va_end(ap);
}

/* get_compiled_pattern: return pointer to compiled pattern from command
   buffer */
pattern_t *
get_compiled_pattern(void)
{
        static pattern_t *expr = NULL;

        char *exps;
        char delimiter;
        int n;

        if ((delimiter = *ibufp) == ' ') {
                seterrmsg("invalid pattern delimiter");
                return NULL;
        } else if (delimiter == '\n' || *++ibufp == '\n' || *ibufp == delimiter) {
                if (!expr) seterrmsg("no previous pattern");
                return expr;
        } else if ((exps = extract_pattern(delimiter)) == NULL)
                return NULL;
        /* buffer alloc'd && not reserved */
        if (expr && !patlock)
                regfree(expr);
        else if ((expr = (pattern_t *) malloc(sizeof(pattern_t))) == NULL) {
                fprintf(stderr, "%s\n", strerror(errno));
                seterrmsg("out of memory");
                return NULL;
        }
        patlock = 0;
        if ((n = regcomp(expr, exps, ere)) != 0) {
                regerror(n, expr, errmsg, sizeof errmsg);
                free(expr);
                return expr = NULL;
        }
        return expr;
}


/* extract_pattern: copy a pattern string from the command buffer; return
   pointer to the copy */
char *
extract_pattern(int delimiter)
{
        static char *lhbuf = NULL;      /* buffer */
        static int lhbufsz = 0;         /* buffer size */

        char *nd;
        int len;

        for (nd = ibufp; *nd != delimiter && *nd != '\n'; nd++)
                switch (*nd) {
                default:
                        break;
                case '[':
                        if ((nd = parse_char_class(nd + 1)) == NULL) {
                                seterrmsg("unbalanced brackets ([])");
                                return NULL;
                        }
                        break;
                case '\\':
                        if (*++nd == '\n') {
                                seterrmsg("trailing backslash (\\)");
                                return NULL;
                        }
                        break;
                }
        len = nd - ibufp;
        REALLOC(lhbuf, lhbufsz, len + 1, NULL);
        memcpy(lhbuf, ibufp, len);
        lhbuf[len] = '\0';
        ibufp = nd;
        return (isbinary) ? NUL_TO_NEWLINE(lhbuf, len) : lhbuf;
}


/* parse_char_class: expand a POSIX character class */
char *
parse_char_class(char *s)
{
        int c, d;

        if (*s == '^')
                s++;
        if (*s == ']')
                s++;
        for (; *s != ']' && *s != '\n'; s++)
                if (*s == '[' && ((d = *(s+1)) == '.' || d == ':' || d == '='))
                        for (s++, c = *++s; *s != ']' || c != d; s++)
                                if ((c = *s) == '\n')
                                        return NULL;
        return  (*s == ']') ? s : NULL;
}